BEIJING China on Friday acknowledged for the first time that it is communicating with the United States about Ling Wancheng, the brother of a disgraced one-time aide to former President Hu Jintao, in a case that could complicate ties.
Authorities have been tight-lipped about revealing any information about Ling, who is in the United States, sources have told Reuters.
China has demanded his return, the New York Times had earlier reported, in a case that could strain Sino-U.S. ties if he were to seek to defect.
The government has given no details of any crime Ling is suspected of and he has not appeared on any wanted lists, but two of his brothers have been accused of corruption, including a former senior aide to President Xi Jinping's predecessor Hu Jintao.
Last month, Liu Jianchao, who runs the ruling Communist Party's anti-graft watchdog's team trying to repatriate graft suspects, told reporters Ling's case had nothing to do with him and he did not know who was in charge of it.
But on Friday, in response to a question from Reuters at a news conference, Liu confirmed for the first time contacts with the United States about the case.
"As for the case of Ling Wancheng, the Chinese side is handling it and is communicating with the United States," Liu said.
Ling was in the United States, Liu told Reuters later. He praised a "very positive" U.S. attitude on anti-corruption cooperation.
Peter Carr, a spokesman for the U.S. Justice Department, said the United States and China "regularly engage on law enforcement matters of mutual concern, including fugitives and anti-corruption".
However, he added: "We do not go into the details of those discussions.”
Gabrielle Price, a spokeswoman for the U.S. State Department, said China had provided the United States with a number of specific cases of concern, and added:
"All cases must be supported by sufficient evidence and work their way through the judicial system in accordance with applicable law."
Last July, China said it would prosecute Ling's brother, Ling Jihua, a former senior aide to Hu, after an investigation found that he had taken bribes and engaged in other corrupt behaviour.
Another brother, Ling Zhengce, has also been accused of corruption.
Since assuming power in late 2012, Xi Jinping has pursued a relentless campaign against corruption, warning that the problem could threaten the party's ability to retain power, though some analysts say he is also eliminating rivals.
Ling Jihua's case has presented a dilemma for Beijing. His position is particularly sensitive because of his connection with Hu.
China's efforts at repatriating corrupt officials overseas have long been hampered by Western countries' reluctance to sign extradition deals, partly out of concern about its judicial system.
Rights groups say Chinese authorities use torture and the death penalty is common in corruption cases.
(Reporting by Michael Martina in Beijing and Julia Harte and David Brunnstrom in Washington; Writing by Sui-Lee Wee; Editing by Robert Birsel and Sandra Maler)